Christian Heimes firstname.lastname@example.org wrote:
Am 29.12.2011 12:13, schrieb Mark Shannon:
The attack relies on being able to predict the hash value for a given string. Randomising the string hash function is quite straightforward. There is no need to change the dictionary code.
A possible (*untested*) patch is attached. I'll leave it for those more familiar with unicodeobject.c to do properly.
I'm worried that hash randomization of str is going to break 3rd party software that rely on a stable hash across multiple Python instances. Persistence layers like ZODB and cross interpreter communication channels used by multiprocessing may (!) rely on the fact that the hash of a string is fixed.
Software that depends on an undefined hash function for synchronization and persistence deserves to break, IMO. There are plenty of well-defined hash functions available for this purpose.